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Ferroelectric Random Access Memory (FeRAM). George Allen Carl Stanfield Guanye Zheng EECS 373 Presentation University of Michigan 11/27/2012. http://www.symetrixcorp.com/lib/images/Devices/SuperLatice_01.jpg. History Dudley Allen Buck, graduate thesis, MIT 1952
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Ferroelectric Random Access Memory (FeRAM) George Allen Carl Stanfield Guanye Zheng EECS 373 Presentation University of Michigan 11/27/2012 http://www.symetrixcorp.com/lib/images/Devices/SuperLatice_01.jpg
History Dudley Allen Buck, graduate thesis, MIT 1952 "Ferroelectrics for Digital Information Storage and Switching" - http://hdl.handle.net/1721.3/40244
Is FeRAM just a fancy version of DDR? DDR • 1T-1C cell • dielectric layer • read requires cap refresh • volatile • <50nm • refresh ~65ms FeRAM • 1T-1C cell • ferroelectric layer (PZT) • read requires cap refresh • non-volatile (sorta) • 130nm • refresh not needed
Read/Write process Read force cell to '0' state reorientation of atoms causes a pulse sent to driveline prior state was '1' - pulse is detected prior state was '0' - pulse not detected refresh state Write charge forces a polarity change
Why FRAM? Rough Comparison (1st generation) source: TI's presentation on FRAM
More Detailed / Overall Memory Products Comparison source:http://www.fujitsu.com/emea/services/microelectronics/fram/technology/
Memory Product Comparison On Power and Size source: presentation (titled Novel Memory Architectures) by Insoo Kim / Feng Wang, The Penn State Universitym on Mar. 23th, 2005
FRAM vs EEPROM 1/30,000 Write Time 1/20 Energy -- 1/400 Power source: http://www.fujitsu.com/emea/services/microelectronics/fram/technology/
FRAM vs EEPROM 100,000 Times Better ENDURANCE source: http://www.fujitsu.com/emea/services/microelectronics/fram/technology/
FRAM vs FLASH Less Power and Faster Speed source: http://www.ti.com.cn/mcu/cn/docs/mcuproductcontentnp.tsp?familyId=1751§ionId=95&tabId=2840&family=mcu
FRAM vs FLASH Much Better Endurance source: http://www.ti.com.cn/mcu/cn/docs/mcuproductcontentnp.tsp?familyId=1751§ionId=95&tabId=2840&family=mcu
FRAM vs SRAM SRAM is better at: Price & Speed(not that much) FRAM is more Flexible (all-in-one memories) source: http://www.ti.com.cn/mcu/cn/docs/mcuproductcontentnp.tsp?familyId=1751§ionId=95&tabId=2840&family=mcu
FRAM vs DRAM When density and price are most important (for example, memories for pixels) DRAM is best choice FRAM cannot replace DRAM yet
FRAM getting better at density! Currently: up to 4Mbits (according to TI's data) Not as good as DRAM and SRAM Better than EEPROM and FLASH Expected: As good as DRAM
Take-away Point: FRAM combines Advantages! source: http://www.ti.com.cn/mcu/cn/docs/mcuproductcontentnp.tsp?familyId=1751§ionId=95&tabId=2840&family=mcu
Application Benefits • Low Power Consumption • Good For: Low energy access systems • Reason: Write cycles require less power (RFID) • Fast Write Speed • Good For: High noise environment • Reason: Short write time limits window of vulnerability • High Endurance • Good For: Diagnostic and maintenance systems • Reason: No restriction of system state writes • Misc • Resistant to Gamma Radiation (70kGray) unlike EEPROM • AEC-Grade 1 adder cheaper than other nonvolatile memory
Application Drawbacks • Low Storage Density • Bad For: Storing large amounts of data • Reason: Poor density compared to DRAM & SRAM • Higher Cost
Current Applications • Automotive • Shift-by-Wire/Navigation/Anti-Pinch Control • Computing • Solid State Drive/LAN Bypass/Network Router http://www.ramtron.com/applications/computing.aspx
Current Applications • Metering • Advanced Metering/Gaming/POS Systems • Industrial • Motion Control/Process Controls • RFID/Wireless Memory • Wireless Datalogging/Gamma Radiation http://www.ramtron.com/applications/metering.aspx
The Future of FRAM • Improved Storage Density • Stacking • 3D integration • Improved Manufacturing Process • Conventional process degrades ferroelectric layer • Reduction in Size • Unknown charge density detection limit • Theoretical performance unclear